Bonnie and Clyde drive into a hay field (in 1933) and are surrounded by modern (for 1967) hay bales tied with twine. The type of hay baler needed to make these bales didn't come into use until the 1940s.
On the opening credits, the card giving Bonnie's background mentions that she was born in Rowena which is in west Texas, just outside San Angelo. When Bonnie and Clyde are in the café and Clyde is talking about her background, he says, "You were born around east Texas, right?" to which she incorrectly responds, "Yeah."
In the scene with the homeowner being evicted by the Midlothian National Bank, after the two homeowners shoot the gun, the homeowner hands the gun to Clyde handle end first, and the very next scene shows Clyde grabbing the barrel of the pistol.
Before crossing the state line into Oklahoma, the Barrow gang robs a bank. When they get into the getaway car and start driving, the scene is cut away several times and each time, the car is pushed back from where it was before.
When Bonnie says to C.W. that the car is a "stolen, four-cylinder Ford coupe," she has her left arm leaning on the car door and the right one inside. In the following shot she has her arms crossed on the door.
After the Texas Ranger spits on Bonnie's face, she then tries to rub the spit off moving her hands downwards as she is still wearing the hat. On the next scene as she finishes rubbing off the spit, suddenly she is not wearing that hat.
Near the end of the movie, as they are riding on their car, Bonnie picks up a pear from a grocery bag and starts eating it. In the following shot, she shares the pear with Clyde but the pear is upside down.
After he calls Bonnie to follow him, Clyde turns and goes to the car. Then she calls him and points to him with her left hand, keeping her right arm by her side. The next shot shows her with her right hand touching her own shoulder.
About 50 minutes into the film Bonnie tells Clyde to pull the car over. Clyde drives into a field and they both get out, walk a way behind the car and start squabbling about getting rid of Buck's wife. Bonnie's hair is messed up and a few strands are draped back to front and more hair is hanging down the middle of her face. Scene cuts to Clyde momentarily then right back to Bonnie - with her hair out of her face and the back to front strands are gone.
While fleeing Texas law enforcement after a bank robbery, the gang drives into Oklahoma on dry land instead of over a bridge, as one might expect. The substantial Red River forms the boundary between Oklahoma and the parts of Texas (northeast and north-central) in which they were active criminals. The dry-land section of the Texas-Oklahoma boundary lies to the north and east of the Texas "Panhandle" which is quite far (about 200 miles at the least) from any of their known bank robberies.
During the tourist court shoot out, the signage states they are in Platte City, Iowa. In actuality the shootout took place near Platte City, Missouri, and near the present day Kansas City International Airport. The approximate location of the tourist court is near Interstate 29 & NW Cookingham Dr. The tourist court has since been torn down.
The film portrays Texas Ranger Frank Hamer as a vengeful bungler who had been captured, humiliated, and released by Bonnie and Clyde. In reality, Hamer was already a legendary Texas Ranger when he was coaxed out of semi-retirement to hunt down the duo, and never met either of them until the moment he and his posse successfully ambushed and killed them near Gibsland, Louisiana in 1934. In 1968, Hamer's widow and son sued the movie producers for defamation of character over his portrayal and were awarded an out of court settlement in 1971.
The police car that rolls during the chase across the Oklahoma border, has an obvious dummy in the front passenger seat. Which can be seen as the car rolls. The only other occupant is the stunt driver.
When C.W. throws a grenade at the armored car it hits the front fender, and the fender breaks in half before the explosion. Since the car is presumably a heavy steel vehicle, (which it was in real life) the light weight grenade shouldn't have broken the fender.
When the Bonnie and Clyde gang takes a break to secretly meet with Bonnie's mother and other relatives, they are outside in the secluded Texas countryside, playing, having a picnic, and enjoying themselves. It is hot outside, and we see parched earth and dry grass. As Clyde talks to old Mrs. Parker, he opens the wrapper to an Eskimo Pie and casually bites into the chocolate-coated vanilla ice cream as he talks. There is no means of refrigeration anywhere and it would have been liquid in that heat.